The suspect has been accused of punching a 72-year-old in the stomach and then robbing him, has been described as 'an olive-skinned man' in his late teens or early 20s.
Police are also looking for a white woman, of a similar age who was involved in the incident.
At around 7.30pm on Saturday (9/3) the victim, a 72-year-old man, was sat on a bench on Wendover Road near to the junction with Marroway.
He was approached by a man and a woman and who briefly spoke with him. The man then punched the victim in the stomach, causing him to drop the bags he was carrying. The woman then went through his shopping bags.
The man and the woman then walked off in the direction of Station Road.
Nothing was taken during the incident and the victim did not require hospital treatment.
The first offender is described as an olive-skinned man in his late teens or early twenties, about 5ft 4ins-5ft 6ins tall and is of a slim build. He was wearing a hooded top with the hood up, tight trousers and trainers.
The second offender is described a white woman in her late teens or early twenties, about 5ft 4ins-5ft 6ins tall and is of a slim build. She was wearing a hooded top, tight jeans and trainers.
Investigating officer Detective Constable Rachel Huggins, based at Aylesbury police station, said: “I am appealing for any information that could help with my investigation into this appalling offence.
“The victim was understandably left very shaken by this incident and I would like to urge local residents, and anyone passing the area on Saturday evening, to check dash-cam footage to see whether you have captured the offence or anyone matching these descriptions.
“You can provide information using our online form or by calling 101. You will need to quote reference number 43190073878. Alternatively, you can contact Crimestoppers anonymously on 0800 555 111.”